As disclosed in JP-A 57-63310, JP-A 58-83006 and JP-A 61-78803, there is known a process for obtaining a highly stereoregular polymer by polymerizing an α-olefin in the presence of a catalyst comprising a combination of the following catalyst components:
(1) a support type solid catalyst component obtained by supporting a tetravalent titanium halide compound on a magnesium halide,
(2) an organoaluminum compound (co-catalyst) and
(3) an organosilicon compound (third component).
Further, as disclosed in JP-A 7-216017, there is also known a process for obtaining a highly stereoregular polymer by polymerizing an α-olefin in the presence of a catalyst comprising a combination of the following catalyst components:
(1) a solid catalyst component obtained according to a process comprising the steps of:
(i) reducing a titanium compound with an organomagnesium compound in the presence of an organosilicon compound and an ester compound to obtaining a solid product,
(ii) treating said solid product with an ester compound, and
(iii) treating the treated product with either a mixture of an ether compound and titanium tetrachloride, or a mixture of an ether compound, titanium tetrachloride and an ester compound to obtain the desired solid catalyst component containing a trivalent titanium compound,
(2) an organoaluminum compound (co-catalyst) and
(3) an organosilicon compound (third component).
Furthermore, as disclosed in JP-A 10-212319, there is also known a process for obtaining a highly stereoregular polymer by polymerizing an α-olefin in the presence of a catalyst comprising a combination of the following catalyst components:
(1) a solid catalyst component obtained according to a process comprising the steps of:
(i) reducing a titanium compound with an organomagnesium compound in the presence of an organosilicon compound and an ester compound to obtain a solid product,
(ii) treating said solid product with a mixture of an ether compound and titanium tetrachloride,
(iii) further treating the treated product with an organic acid halide compound, and
(iv) still further treating the resulting treated product with either a mixture of an ether compound and titanium tetrachloride, or a mixture of an ether compound, titanium tetrachloride and an ester compound to obtain the desired solid catalyst component containing a trivalent titanium compound,
(2) an organoaluminum compound (co-catalyst) and
(3) an organosilicon compound (third component).
According to the above-mentioned processes, a highly stereoregular polymer can be produced through a no-extraction/no-deash process. However, it is desired to further improve a quality of the highly stereoregular polymer.